1. Field of the Invention
The present invention relates to vacuum cleaners, and, more specifically, to devices for performing cleaning operations along the edges of the vacuum cleaner's cleaning path.
2. Description of the Related Art
Upright vacuum cleaners are characterized by a base adapted to move along a floor, and a handle pivotally attached to the base (in some rare instances, the handle may be at a fixed angle to the base). The base and handle form one or more enclosures that contain a suction motor (a combined electric motor and impeller fan), a dirt collection system (e.g., a bag chamber or a cyclonic or inertial separation system), and one or more airflow passages to convey dirt-laden air through the dirt collection system. The suction motor and dirt collection system may be located in the base or the handle, and the airflow passages may comprise a series of rigid pipes, chambers, flexible hoses, and the like, as known in the art.
In a typical upright vacuum cleaner, the airflow passage system has a main inlet for cleaning large areas of the floor. The vacuum cleaner also may include an auxiliary inlet located on a flexible hose to permit cleaning in tight spaces and above the floor. The main inlet is located at the bottom of the base, and usually is elongated in the lateral direction (that is, the direction perpendicular to the fore-aft direction of movement) so as to vacuum a wide path as the cleaner is moved back and forth on the floor.
The main inlet often is effective at removing dirt from a cleaning path located directly below the main inlet, but is less effective at removing dirt located at or beyond the main inlet's lateral edges. This may be due to reduced airflow velocity at the lateral edges of the main inlet, occluded airflow at the lateral edge regions, or other factors. Reduced edge cleaning efficiency is not a problem for cleaning open areas, as the main inlet can be moved back and forth along laterally overlapping paths to fully clean the area. Edge cleaning effectiveness can, however, become a problem along walls, furniture, and other obstacles that prevent the user from passing the main inlet directly over the floor. This problem is magnified on carpeted floors, due to the carpet interfering with the free movement of air to entrain dirt embedded in the carpet fibers. Effective edge cleaning also may become more problematic with increased distances between the lateral side of the base and the lateral edge of the main inlet. For example, some upright vacuum cleaners have wheels or brush drive assemblies located between the edge of the main inlet and the outer edge of the base, thus increasing the distance that the dirt must travel to be sucked into the main inlet.
Prior vacuum cleaning systems have attempted to enhance edge cleaning performance by providing airflow passages that concentrate the suction along one or both edges of the base. For example, U.S. Pat. No. 3,942,216 shows a vacuum cleaning head having a small side inlet at each lateral end of the main inlet, and a valve to selectively direct the airflow to either side inlet for edge cleaning. This manually-operated device requires the user to bend down and turn the valve whenever edge cleaning is desired. Another edge cleaning device is shown in U.S. Pat. No. 6,039,817, which shows edge cleaning openings located near the edges of the main inlet, and a variety of different configurations to selectively direct the airflow to the edge inlets. Other examples of edge cleaning systems are shown in U.S. Pat. Nos. 3,205,528; 7,124,467 and 7,134,164 and U.K. Application No. GB4378643A. The foregoing are all incorporated by reference herein.
Despite earlier efforts to provide effective edge cleaning systems, there still exists a need to provide a simple, reliable and effective edge cleaning system that can be incorporated into upright vacuum cleaners or other cleaning systems.